Coiled Tube Drilling Bottom Hole Assembly Having Wireless Power And Data Connection

ABSTRACT

Various embodiments of methods and systems for providing wireless power and data communication in a drilling assembly. One embodiment includes a system for transmitting power or data communications in a drill string. The system includes a drilling assembly having an inner cylindrical coil located inside an outer cylindrical coil. The inner cylindrical coil is adapted to rotate with respect to the outer cylindrical coil, rotate around an axis of the outer cylindrical coil, or move axially with respect to the outer cylindrical coil.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/704,599, entitled “Coiled Tube Drilling Bore Hole Assembly With A Wireless Power and Data Connection,” and filed on Sep. 24, 2012, U.S. Provisional Patent Application Ser. No. 61/704,805, entitled “System And Method For Wireless Power And Data Transmission In A Mud Motor,” and filed on Sep. 24, 2012, and U.S. Provisional Patent Application Ser. No. 61/704,758, entitled “Positive Displacement Motor Rotary Steerable System And Apparatus,” and filed on Sep. 24, 2012, the disclosures of which are hereby incorporated by reference in their entireties.

DESCRIPTION OF THE RELATED ART

In preparing wells in drilling operations, boreholes are drilled to subterranean reservoirs, and those boreholes can be used for producing desired fluids, such as hydrocarbon-based fluids. The boreholes can be used for treatment and other applications. In many environments, directional drilling systems are used to enable an operator to change direction of the drilling to better access reservoir or other subterranean regions.

A variety of systems and techniques are used to facilitate directional drilling. For example, coiled tube drilling (CTD) systems have been used to provide the flexibility needed to drill deviated wellbores. Additionally, a variety of systems and devices, including steerable motors, articulated subs, push-the-bit systems, and other systems or devices have been used to facilitate steering of the drilling operation. Although the market for CTD systems and applications has grown in recent years, existing downhole drilling bottom hole assemblies (BHAs) have largely failed to leverage the existing coil tubing rigs and improve the cost and performance of CTD drilling operations.

Existing CTD solutions have significant limitations and/or fail to address key segments of the market. Baker-Hughes “Coil-Trak” systems use a modular, steerable motor, measurement BHA, with a non-continuous, bi-directional orienter just above the steerable motor, all powered and with telemetry via wire-line to the surface. Baker Hughes has another solution involving a rib-steer CTD BHA, which is capable of continuous rotation, but at lower dog-legs than the Coil-Trak solution. Other conventional solutions may include an articulated sub for drilling curved bore-hole, a thruster for providing force to advance the drill bit, an orienter, and a measure-while-drilling (MWD).

Despite the growth of CTD systems, existing solutions have failed to leverage the existing coil tubing rigs and improve the cost and performance of CTD drilling operations. Accordingly, there is a need in the art for improved CTD bottom hole assemblies.

SUMMARY OF THE DISCLOSURE

Various embodiments of methods and systems are disclosed for providing wireless power and data communication in a drilling assembly. One embodiment includes a system for transmitting power or data communications in a drill string. The system includes a drilling assembly having an inner cylindrical coil located inside an outer cylindrical coil. The inner cylindrical coil is adapted to rotate with respect to the outer cylindrical coil, rotate around an axis of the outer cylindrical coil, or move axially with respect to the outer cylindrical coil.

Another embodiment includes a bottom hole assembly (BHA) for use in a coiled tube drilling system. The BHA includes a measuring-while-drilling (MWD) module and a wireless power and data connection. The MWD module is configured for coupling to coiled tubing. The wireless power and data connection is disposed above a drilling motor for providing power and data connectivity between the MWD module and the drilling motor.

This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Figures, like reference numerals refer to like parts throughout the various views unless otherwise indicated. For reference numerals with letter character designations such as “102A” or “102B”, the letter character designations may differentiate two like parts or elements present in the same figure. Letter character designations for reference numerals may be omitted when it is intended that a reference numeral to encompass all parts having the same reference numeral in all figures.

FIG. 1A is a diagram of a system for enabling wireless power and data transfer between components in a drilling operation.

FIG. 1B is a diagram of a wellsite drilling system that forms part of the system illustrated in FIG. 1A.

FIG. 2 is a schematic drawing depicting a primary or transmitting circuit and a secondary or receiving circuit.

FIG. 3 is a schematic drawing depicting a primary or transmitting circuit and a secondary or receiving circuit with transformers having turn ratios N_(S):1 and N_(L):1 that may used to match impedances.

FIG. 4 is a schematic drawing depicting an alternative circuit to that which is depicted in FIG. 3 and having parallel capacitors that are used to resonate the coils' self-inductances.

FIGS. 5A-5B illustrate an embodiment of a receiving coil inside a transmitting coil.

FIGS. 6-7 are graphs illustrating the variation in k versus axial displacement of the receiving coil when x=0 is small and the transverse displacement when z=produces very small changes in k of given embodiments, respectively.

FIGS. 8-9 are graphs illustrating that power efficiency may also be calculated for displacements from the center in the z direction and in the x direction, respectively, of given embodiments.

FIG. 10 is a graph illustrating that the sensitivity of the power efficiency to frequency drifts may be relatively small in some embodiments.

FIG. 11 is a graph illustrating that drifts in the components values of some embodiments do not have a large effect on the power efficiency of the embodiment.

FIG. 12 depicts a particular embodiment configured to convert input DC power to a high frequency AC signal, f₀, via a DC/AC convertor.

FIG. 13 depicts a particular embodiment configured to pass AC power through the coils.

FIG. 14 depicts a particular embodiment that includes additional secondary coils configured to transmit and receive data.

FIG. 15 is a diagram of an embodiment of a coiled tube drilling system that includes a CTD BHA for enabling wireless power and data transfer between components in the CTD BHA.

FIG. 16 is a diagram illustrating an embodiment of the CTD BHA of FIG. 15 that includes a wireless power and data connection for enabling wireless power and data transfer between components in the CTD BHA.

FIG. 17 is a diagram illustrating another embodiment of the CTD BHA of FIG. 15.

FIG. 18 is a diagram illustrating a more detailed view of the MWD module and the wireless power and data connection in FIGS. 16 & 17.

FIG. 19 is a diagram illustrating another embodiment of the CTD BHA of FIG. 15, which includes an orienter operatively coupled to the wireless power and data connection.

FIG. 20 is a diagram illustrating a more detailed view of the orienter and the wireless power and data connection of FIG. 19.

DETAILED DESCRIPTION

Various embodiments of systems and methods are disclosed for providing power and/or data communications in drilling assembly. Referring initially to FIG. 1A, this figure is a diagram of a system 102 for enabling wireless power and data transfer between components in a drilling operation. The system 102 includes a controller module 101 that is part of a controller 106. The system 102 also includes a drilling system 104, which has a logging and control module 95, a bottom hole assembly (“BHA”) 100, and wireless power and data connections 204. The controller 106 further includes a display 147 for conveying alerts 110A and status information 115A that are produced by an alerts module 110B and a status module 115B. The controller 102 may communicate with the drilling system 104 via a communications network 142.

The controller 106 and the drilling system 104 may be coupled to the communications network 142 via communication links 103. Many of the system elements illustrated in FIG. 1A are coupled via communications links 103 to the communications network 142.

The links 103 illustrated in FIG. 1A may include wired or wireless couplings or links. Wireless links include, but are not limited to, radio-frequency (“RF”) links, infrared links, acoustic links, and other wireless mediums. The communications network 142 may include a wide area network (“WAN”), a local area network (“LAN”), the Internet, a Public Switched Telephony Network (“PSTN”), a paging network, or a combination thereof. The communications network 142 may be established by broadcast RF transceiver towers (not illustrated). However, one of ordinary skill in the art recognizes that other types of communication devices besides broadcast RF transceiver towers are included within the scope of this disclosure for establishing the communications network 142.

The drilling system 104 and controller 106 of the system 102 may have RF antennas so that each element may establish wireless communication links 103 with the communications network 142 via RF transceiver towers (not illustrated). Alternatively, the controller 106 and drilling system 104 of the system 102 may be directly coupled to the communications network 142 with a wired connection. The controller 106 in some instances may communicate directly with the drilling system 104 as indicated by dashed line 99 or the controller 106 may communicate indirectly with the drilling system 104 using the communications network 142.

The controller module 101 may include software or hardware (or both). The controller module 101 may generate the alerts 110A that may be rendered on the display 147. The alerts 110A may be visual in nature but they may also include audible alerts as understood by one of ordinary skill in the art.

The display 147 may include a computer screen or other visual device. The display 147 may be part of a separate stand-alone portable computing device that is coupled to the logging and control module 95 of the drilling system 104. The logging and control module 95 may include hardware or software (or both) for direct control of a bottom hole assembly 100 as understood by one of ordinary skill in the art.

FIG. 1B illustrates a wellsite drilling system 104 that forms part of the system 102 illustrated in FIG. 1A. The wellsite can be onshore or offshore. In this system 104, a borehole 11 is formed in subsurface formations by rotary drilling in a manner that is known to one of ordinary skill in the art. Embodiments of the system 104 can also use directional drilling, as will be described hereinafter. The drilling system 104 includes the logging and control module 95 as discussed above in connection with FIG. 1A.

A drill string 12 is suspended within the borehole 11 and has a bottom hole assembly (“BHA”) 100 which includes a drill bit 105 at its lower end. The surface system includes platform and derrick assembly 10 positioned over the borehole 11, the assembly 10 including a rotary table 16, kelly 17, hook 18 and rotary swivel 19. The drill string 12 is rotated by the rotary table 16, energized by means not shown, which engages the kelly 17 at the upper end of the drill string. The drill string 12 is suspended from a hook 18, attached to a traveling block (also not shown), through the kelly 17 and a rotary swivel 19 which permits rotation of the drill string 12 relative to the hook 18. As is known to one of ordinary skill in the art, a top drive system could alternatively be used instead of the kelly 17 and rotary table 16 to rotate the drill string 12 from the surface. The drill string 12 may be assembled from a plurality of segments 125 of pipe and/or collars threadedly joined end to end.

In the embodiment of FIG. 1B, the surface system further includes drilling fluid or mud 26 stored in a pit 27 formed at the well site. A pump 29 delivers the drilling fluid 26 to the interior of the drill string 12 via a port in the swivel 19, causing the drilling fluid to flow downwardly through the drill string 12 as indicated by the directional arrow 8. The drilling fluid exits the drill string 12 via ports in the drill bit 105, and then circulates upwardly through the annulus region between the outside of the drill string and the wall of the borehole, as indicated by the directional arrows 9. In this system as understood by one of ordinary skill in the art, the drilling fluid 26 lubricates the drill bit 105 and carries formation cuttings up to the surface as it is returned to the pit 27 for cleaning and recirculation.

The bottom hole assembly 100 of the illustrated embodiment may include a logging-while-drilling (LWD) module 120, a measuring-while-drilling (MWD) module 130, a rotary-steerable system and motor 150, and drill bit 105.

The LWD module 120 is housed in a special type of drill collar, as is known to one of ordinary skill in the art, and can contain one or a plurality of known types of logging tools. It will also be understood that more than one LWD 120 and/or MWD module 130 can be employed, e.g. as represented at 120A. (References, throughout, to a module at the position of 120A can alternatively mean a module at the position of 120B as well.) The LWD module 120 includes capabilities for measuring, processing, and storing information, as well as for communicating with the surface equipment. In the present embodiment, the LWD module 120 includes a directional resistivity measuring device.

The MWD module 130 is also housed in a special type of drill collar, as is known to one of ordinary skill in the art, and can contain one or more devices for measuring characteristics of the drill string 12 and drill bit 105. The MWD module 130 may further includes an apparatus (not shown) for generating electrical power to the downhole system 100.

This apparatus may typically include a mud turbine generator powered by the flow of the drilling fluid 26, it being understood by one of ordinary skill in the art that other power and/or battery systems may be employed. In the embodiment, the MWD module 130 includes one or more of the following types of measuring devices: a weight-on-bit measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a stick slip measuring device, a direction measuring device, and an inclination measuring device.

The foregoing examples of wireline and drill string conveyance of a well logging instrument are not to be construed as a limitation on the types of conveyance that may be used for the well logging instrument. Any other conveyance known to one of ordinary skill in the art may be used, including without limitation, slickline (solid wire cable), coiled tubing, well tractor and production tubing.

FIGS. 2-14 illustrate various embodiments for implementing the wireless power and data connection 204. It should be appreciated that the wireless power and data connection 204 may be incorporated in various types and configurations of drilling assemblies, including, for example, coiled tube drilling (CTD) installations, such as described below with reference to FIGS. 15-20.

FIG. 2 is a schematic drawing depicting a primary or transmitting circuit 210 and a secondary or receiving circuit 220. In this description, the time dependence is assumed to be exp(jωt) where ω=2πf and f is the frequency in Hertz. Returning to the FIG. 2 illustration, the transmitting coil is represented as an inductance L₁ and the receiving coil as L₂. In the primary circuit 210, a voltage generator with constant output voltage V_(S) and source resistance R_(S) drives a current I₁ through a tuning capacitor C₁ and primary coil having self-inductance L₁ and series resistance R₁. The secondary circuit 220 has self-inductance L₂ and series resistance R₂. The resistances, R₁ and R₂, may be due to the coils' wires, to losses in the coils magnetic cores (if present), and to conductive materials or mediums surrounding the coils. The Emf (electromotive force) generated in the receiving coil is V₂, which drives current I₂ through the load resistance R_(L) and tuning capacitor C₂. The mutual inductance between the two coils is M, and the coupling coefficient k is defined as:

k=M/√{square root over (L₁ L ₂)}  (1)

While a conventional inductive coupler has k≈1, weakly coupled coils may have a value for k less than 1 such as, for example, less than or equal to about 0.9. To compensate for weak coupling, the primary and secondary coils in the various embodiments are resonated at the same frequency. The resonance frequency is calculated as:

$\begin{matrix} {\omega_{0} = {\frac{1}{\sqrt{L_{1}C_{1}}} = \frac{1}{\sqrt{L_{2}C_{2}}}}} & (2) \end{matrix}$

At resonance, the reactance due to L₁ is cancelled by the reactance due to C₁. Similarly, the reactance due to L₂ is cancelled by the reactance due to C₂. Efficient power transfer may occur at the resonance frequency, f₀=ω₀/2π. In addition, both coils may be associated with high quality factors, defined as:

$\begin{matrix} {Q_{1} = {{\frac{\omega \; L_{1}}{R_{1}}\mspace{14mu} {and}\mspace{14mu} Q_{2}} = {\frac{\omega \; L_{2}}{R_{2}}.}}} & (3) \end{matrix}$

The quality factors, Q, may be greater than or equal to about 10 and in some embodiments greater than or equal to about 100. As is understood by one of ordinary skill in the art, the quality factor of a coil is a dimensionless parameter that characterizes the coil's bandwidth relative to its center frequency and, as such, a higher Q value may thus indicate a lower rate of energy loss as compared to coils with lower Q values.

If the coils are loosely coupled such that k<1, then efficient power transfer may be achieved provided the figure of merit, U, is larger than one such as, for example, greater than or equal to about 3:

U=k√{square root over (Q₁ Q ₂)}>>1  (4)

The primary and secondary circuits are coupled together via:

V ₁ =jωL ₁ I ₁ +jωMI ₂ and V ₂ =jωL ₂ I ₂ +jωMI ₁,  (5)

where V₁ is the voltage across the transmitting coil. Note that the current is defined as clockwise in the primary circuit and counterclockwise in the secondary circuit. The power delivered to the load resistance is:

$\begin{matrix} {{P_{L} = {\frac{1}{2}R_{L}{I_{2}}^{2}}},} & (6) \end{matrix}$

while the maximum theoretical power output from the fixed voltage source V_(S) into a load is:

$\begin{matrix} {P_{MAX} = {\frac{{V_{S}}^{2}}{8\; R_{S}}.}} & (7) \end{matrix}$

The power efficiency is defined as the power delivered to the load divided by the maximum possible power output from the source,

$\begin{matrix} {\eta \equiv {\frac{P_{L}}{P_{MAX}}.}} & (8) \end{matrix}$

In order to optimize the power efficiency, η, the source resistance may be matched to the impedance of the rest of the circuitry. Referring to FIG. 2, Z₁ is the impedance looking from the source toward the load and is given by:

$\begin{matrix} {Z_{1} = {R_{1} - {j/\left( {\omega \; C_{1}} \right)} + {j\; \omega \; L_{1}} + \frac{\omega^{2}M^{2}}{R_{2} + R_{L} + {j\; \omega \; L_{2}} - {j/\left( {\omega \; C_{2}} \right)}}}} & (9) \end{matrix}$

When ω=ω₀, Z₁ is purely resistive and may equal R_(S) for maximum efficiency.

$\begin{matrix} {Z_{1} = {{R_{1} + \frac{\omega^{2}M^{2}}{R_{2} + R_{L}}} \equiv {R_{S}.}}} & (10) \end{matrix}$

Similarly, the impedance seen by the load looking back toward the source is

$\begin{matrix} {Z_{2} = {R_{2} - {j/\left( {\omega \; C_{2}} \right)} + {j\; \omega \; L_{2}} + \frac{\omega^{2}M^{2}}{R_{1} + R_{S} + {j\; \omega \; L_{1}} - {j/\left( {\omega \; C_{1}} \right)}}}} & (11) \end{matrix}$

When ω=ω₀, Z₂ is purely resistive and R_(L) should equal Z₂ for maximum efficiency

$\begin{matrix} {Z_{2} = {{R_{2} + \frac{\omega^{2}M^{2}}{R_{1} + R_{S}}} \equiv {R_{L}.}}} & (12) \end{matrix}$

The power delivered to the load is then:

$\begin{matrix} {{P_{L} = {\frac{1}{2}\frac{R_{L}\omega_{0}^{2}M^{2}{V_{S}}^{2}}{\left\lbrack {{\left( {R_{S} + R_{1}} \right)\left( {R_{2} + R_{L}} \right)} + {\omega_{0}^{2}M^{2}}} \right\rbrack^{2}}}},} & (13) \end{matrix}$

and the power efficiency is the power delivered to the load divided by the maximum possible power output,

$\begin{matrix} {{\eta \equiv \frac{P_{L}}{P_{MAX}}} = {\frac{4\; R_{S}R_{L}\omega_{0}^{2}M^{2}}{\left\lbrack {{\left( {R_{S} + R_{1}} \right)\left( {R_{2} + R_{L}} \right)} + {\omega_{0}^{2}M^{2}}} \right\rbrack^{2}}.}} & (14) \end{matrix}$

The optimum values for R_(L) and R_(L) may be obtained by simultaneously solving

$\begin{matrix} {{R_{S} = {{R_{1} + {\frac{\omega^{2}M^{2}}{R_{2} + R_{L}}\mspace{14mu} {and}\mspace{14mu} R_{L}}} = {R_{2} + \frac{\omega^{2}M^{2}}{R_{1} + R_{S}}}}},} & (15) \end{matrix}$

with the result that:

R _(S) =R ₁√{square root over (1+k ² Q ₁ Q ₂)} and R _(L) =R ₂√{square root over (1+k ² Q ₁ Q ₂)}.  (16)

If the source and load resistances do not satisfy equations (16), then it is envisioned that standard methods may be used to transform the impedances. For example, as shown in the FIG. 3 illustration, transformers with turn ratios N_(S):1 and N_(L):1 may be used to match impedances as per equations (16). Alternatively, the circuit illustrated in FIG. 4 may be used. In such an embodiment in FIG. 4, parallel capacitors are used to resonate the coils' self-inductances according to equation (2). As before, Z₁ is defined as the impedance seen by the source looking toward the load, while Z₂ is defined as the impedance seen by the load looking toward the source. In addition, there are two matching impedances, Z_(S) and Z_(T) which may be used to cancel any reactance that would otherwise be seen by the source or load. Hence Z₁ and Z₂ are purely resistive with the proper choices of Z_(S) and Z_(T). Notably, the source resistance R_(S) may equal Z₁, and the load resistance R_(L) may equal Z₂. The procedures for optimizing efficiency with series capacitance or with parallel capacitance may be the same, and both approaches may provide high efficiencies.

Turning now to FIGS. 5A and 5B, a cross sectional view of two coils 232, 234 is illustrated in FIG. 5A and a side view of the two coils 232, 234 is illustrated in FIG. 5B. In these two figures, a receiving coil 232 inside a transmitting coil 234 of a particular embodiment 230 is depicted. The receiving coil 232 includes a ferrite rod core 235 that, in some embodiments, may be about 12.5 mm (about 0.49 inch) in diameter and about 96 mm (about 3.78 inches) long with about thirty-two turns of wire 237. Notably, although specific dimensions and/or quantities of various components may be offered in this description, it will be understood by one of ordinary skill in the art that the embodiments are not limited to the specific dimensions and/or quantities described herein.

Returning to FIG. 5, the transmitting coil 234 may include an insulating housing 236, about twenty-five turns of wire 239, and an outer shell of ferrite 238. The wall thickness of the ferrite shell 238 in the FIG. 5 embodiment may be about 1.3 mm (about 0.05 inch). In certain embodiments, the overall size of the transmitting coil 234 may be about 90 mm (about 3.54 inch) in diameter by about 150 mm (about 5.90 inches) long. The receiving coil 232 may reside inside the transmitting coil 234, which is annular.

The receiving coil 232 may be free to move in the axial (z) direction or in the transverse direction (x) with respect to the transmitting coil 234. In addition, the receiving coil 232 may be able to rotate on axis with respect to the transmitting coil 234. The region between the two coils 232, 234 may be filled with air, fresh water, salt water, oil, natural gas, drilling fluid (known as “mud”), or any other liquid or gas. The transmitting coil 234 may also be mounted inside a metal tube, with minimal affect on the power efficiency because the magnetic flux may be captured by, and returned through, the ferrite shell 238 of the transmitting coil 234.

The operating frequency for these coils 232, 234 may vary according to the particular embodiment, but, for the FIG. 5 example 230, a resonant frequency f=100 kHz may be assumed. At this frequency, the transmitting coil 234 properties are: L₁=6.76·10⁻⁵ Henries and R₁=0.053 ohms, and the receiving coil 232 properties are L₂=7.55·10⁻⁵ Henries and R₂=0.040 ohms. The tuning capacitors are C₁=3.75·10⁻⁸ Farads and C₂=3.36·10⁻⁸ Farads. Notably, the coupling coefficient k value depends on the position of the receiving coil 232 inside the transmitting coil 234. The receiving coil 232 is centered when x=0 and z=0 and there is k=0.64.

The variation in k versus axial displacement of the receiving coil 232 when x=0 may be relatively small, as illustrated by the graph 250 in FIG. 6. The transverse displacement when z=0 may produce very small changes in k, as illustrated by the graph 252 in FIG. 7. The receiving coil 232 may rotate about the z-axis without affecting k because the coils are azimuthally symmetric. According to equations (16), an optimum value for the source resistance may be R_(S)=32 ohms, and for the load resistance may be R_(L)=24 ohms when the receiving coil 232 is centered at x=0 and z=0. The power efficiency may thus be η=99.5%.

The power efficiency may also be calculated for displacements from the center in the z direction in mm (as illustrated by the graph 254 in FIG. 8) and in the x direction in mm (as illustrated by the graph 256 in FIG. 9). It is envisioned that the efficiency may be greater than about 99% for axial displacements up to about 20.0 mm (about 0.79 inch) in certain embodiments, and greater than about 95% for axial displacements up to about 35.0 mm (about 1.38 inches). It is further envisioned that the efficiency may be greater than 98% for transverse displacements up to 20.0 mm (about 0.79 inch) in some embodiments. Hence, the position of the receiving coil 232 inside the transmitting coil 234 may vary in some embodiments without reducing the ability of the two coils 232, 234 to efficiently transfer power.

Referring now to FIG. 10, it can be seen in the illustrative graph 258 where the Y-axis denotes efficiency in percentage and the X-axis denotes frequency in Hz that the sensitivity of the power efficiency to frequency drifts may be relatively small. A ±10% variation in frequency may produce minor effects, while the coil parameters may be held fixed. The power efficiency at 90,000 Hz is better than about 95%, and the power efficiency at 110,000 Hz is still greater than about 99%. Similarly, drifts in the component values may not have a large effect on the power efficiency. For example, both tuning capacitors C₁ and C₂ are allowed to increase by about 10% and by about 20% as illustrated in the graph 260 of FIG. 11. Notably, the other parameters are held fixed, except for the coupling coefficient k. The impact of the power efficiency is negligible. As such, the system described herein would be understood by one of ordinary skill in the art to be robust.

It is also envisioned that power may be transmitted from the inner coil to the outer coil of particular embodiments, interchanging the roles of transmitter and receiver. It is envisioned that the same power efficiency would be realized in both cases.

Referring to FIG. 12, an electronic configuration 262 is illustrated for converting input DC power to a high frequency AC signal, f₀, via a DC/AC convertor. The transmitter circuit in the configuration 262 excites the transmitting coil at resonant frequency f₀. The receiving circuit drives an AC/DC convertor, which provides DC power output for subsequent electronics. This system 262 is appropriate for efficient passing DC power across the coils.

Turning to FIG. 13, AC power can be passed through the coils. Input AC power at frequency f₁ is converted to resonant frequency f₀ by a frequency convertor. Normally this would be a step up convertor with f₀>>f₁. The receiver circuit outputs power at frequency f₀, which is converted back to AC power at frequency f₁. Alternatively, as one of ordinary skill in the art recognizes, the FIG. 13 embodiment 264 could be modified to accept DC power in and produce AC power out, and vice versa.

In lieu of, or in addition to, passing power, data signals may be transferred from one coil to the other in certain embodiments by a variety of means. In the above example, power is transferred using an about 100.0 kHz oscillating magnetic field. It is envisioned that this oscillating signal may also be used as a carrier frequency with amplitude modulation, phase modulation, or frequency modulation used to transfer data from the transmitting coil to the receiving coil. Such would provide a one-way data transfer.

An alternative embodiment includes additional secondary coils to transmit and receive data in parallel with any power transmissions occurring between the other coils described above, as illustrated in FIG. 14. Such an arrangement may provide two-way data communication in some embodiments. The secondary data coils 266, 268 may be associated with relatively low power efficiencies of less than about 10%. It is envisioned that in some embodiments the data transfer may be accomplished with a good signal to noise ratio, for example, about 6.0 dB or better. The secondary data coils 266, 268 may have fewer turns than the power transmitting 234 and receiving coils 232.

The secondary data coils 266, 268 may be orthogonal to the power coils 232, 234, as illustrated in FIG. 14. For example, the magnetic flux from the power transmitting coils 232, 234 may be orthogonal to a first data coil 266, so that it does not induce a signal in the first data coil 266. A second data coil 268 may be wrapped as shown in FIG. 14 such that magnetic flux from the power transmitters does not pass through it, but magnetic flux from first data coil 266 does. Notably, the configuration depicted in FIG. 14 is offered for illustrative purposes only and is not meant to suggest that it is the only configuration that may reduce or eliminate the possibility that a signal will be induced in one or more of the data coils by the magnetic flux of the power transmitting coils. Other data coil configurations that may minimize the magnetic flux from the power transmitter exciting the data coils will occur to those with ordinary skill in the art.

Moreover, it is envisioned that the data coils 266, 268 may be wound on a non-magnetic dielectric material in some embodiments. Using a magnetic core for the data coils 266, 268 might result in the data coils' cores being saturated by the strong magnetic fields used for power transmission. Also, the data coils 266, 268 may be configured to operate at a substantially different frequency than the power transmission frequency. For example, if the power is transmitted at about 100.0 kHz in a certain embodiment, then the data may be transmitted at a frequency of about 1.0 MHz or higher. In such an embodiment, high pass filters on the data coils 266, 268 may prevent the about 100.0 kHz signal from corrupting the data signal. In still other embodiments, the data coils 266, 268 may simply be located away from the power coils 232, 234 to minimize any interference from the power transmission. It is further envisioned that some embodiments may use any combination of these methods to mitigate or eliminate adverse effects on the data coils 266, 268 from the power transmission of the power coils 232, 234.

Having described the structure and operation of various embodiments of the wireless power and data connection 204 with reference to FIGS. 2-14, various embodiments of coiled tube drilling (CTD) systems that include a wireless power and data connection 204 will be described with reference to FIGS. 15-20.

FIG. 15 illustrates another embodiment of a coiled tubing drilling (CTD) system 201. The CTD system 201 may include a variety of components and systems. In the embodiment illustrated in FIG. 15, the CTD system 201 generally includes a coiled tubing rig and injector installation 202 positioned at the top of a drilled borehole 206. The CTD system 201 further includes coiled tubing 204 connected to a coiled tubing drilling (CTD) bottom hole assembly 200 (CTD BHA). The CTD BHA 200 includes a variety of components including a drill bit 105 driven to form the borehole and other components including MWD module 130 and LWD module 120. The drill bit 105 may be rotated by a drilling motor or by another suitable driving device. Other components may have a variety of sensors and signal transmission systems to provide an operator with real-time data and/or other data helpful in both drilling the borehole and in steering the CTD BHA 200 along a variety of desired trajectories through a reservoir.

FIGS. 16-20 illustrate various configurations for the CTD BHA 200 for providing wireless power and data connectivity between components in the CTD BHA 200. The BHA configurations illustrate different embodiments for arranging various components within the CTD BHA 200. These and other configurations may provide wireless power and data transfer to components above and/or below a downhole drilling motor 306 (see FIG. 16 described below) and, thereby, advantageously enable real-time measurement and control of various drilling conditions for optimizing drilling performance and/or reducing drilling costs associated with equipment design.

In the embodiment of FIG. 16, the CTD BHA 200 includes a MWD module 130 connected to coiled tubing 204. As known in the art, the coiled tubing 204 and the MWD module 130 slide along an axis (reference numeral 310) but do not rotate. The MWD module 130 includes a system including, for example, power component(s), telemetry component(s), and a directional & inclination (D&I) survey package 307. The downhole end of the MWD module 130 is connected to a drilling motor 306, which is in turn connected to a LWD module 120. The drilling motor 306 may slide (reference numeral 310) but does not rotate.

The CTD BHA 200 further includes a wireless power and data connection 304 associated with the drilling motor 306. The wireless power and data connection 304 includes a wireless, tuned-inductive coupler mechanism for passing both power and data communications to downhole components of the CTD BHA 200. The wireless power and data connection 304 of FIG. 16 (and later FIGS. 17-20) corresponds to wireless connection 204 of FIG. 1A and the embodiments illustrated in FIGS. 2-14 described above. It should be appreciated that separate coils may be used for power and/or communication transmissions. A wired rotor conveys power and data to the BHA components located below the drilling motor 306. A rotating LWD module 120 and rotary steerable system (RSS) 302 may be connected downhole relative to the drilling motor 306. The rotation of the LWD module 120 and the RSS 302 are shown as reference numeral 308. RSS 302 and motor 306 are one embodiment of the rotary-steerable system and motor 150 illustrated in FIG. 1B.

A drill bit 105 is attached to the downhole end of the RSS 302. It should be appreciated that the wireless power and data connection 304 provides relative motion between the MWD module 130 (which is coupled to an external housing of the drilling motor 306) and the rotor of the drilling motor 306 (which is wired and coupled to the RSS/LWD/drill bit assembly), allowing power and data transfer throughout the CTD BHA 200.

Various additional configurations for CTD BHA 200 are illustrated in FIGS. 17-20. In the embodiment of FIG. 17, the LWD module 120 is disposed between the drilling motor 306 and the RSS 302, which may provide an automated system for steering the drill bit 105. The LWD module 120 is located above the drilling motor 306 relative to the embodiment of FIG. 16. It should be appreciated that this configuration may be useful in applications where rotation of the LWD module 120 is not desired.

FIG. 18 illustrates in more detail the wireless power and data connection 304 disposed between the MWD module 130 and the drilling motor 306. Power and data wiring exits the downhole end of the MWD module 130 and is coupled to a stationary coil 506 of the wireless power and data connection 304 located in the drilling motor 306 external housing. Power and data are transmitted between the stationary coil 504 and a rotating coil 506 via tuned-inductive methods. Further details of this wireless and data connection 304 for coils 504, 506 correspond to FIGS. 5A-5B described above. Wiring is coupled to the rotating coil 506 and passes through an interior sealed channel in the center of the rotor 502 of the drilling motor 306. At the bottom of the rotor 502, the wire is terminated at a connection 508 to the rotating BHA. The connection may include a threaded rotary shouldered joint and a sealed electrical connector mechanically and electrically coupling the rotating mechanism of the drilling motor 306 to the rotating BHA.

FIG. 19 illustrates another embodiment of the CTD BHA 200, which includes an orienter 606 integrated with the wireless power and data connection 304. It should be appreciated that an orienter 606 may provide an alternative to using the RSS 302. As known in the art, in certain use cases, more aggressive steering of the drill bit 105 may be desired. The CTD BHA 200 includes the orienter 606, the MWD module 130, the LWD module 120, and a steerable motor 306. In this embodiment of FIG. 19, the motor 306 is positioned directly adjacent to the drill bit 105 while all other components are positioned above the motor 306 relative to the borehole. As known in the art, the motor 306 may rotate the drill bit 105 (arrow 610).

The coiled tubing 204 may house wire-line conductor(s) 602 electrically coupled to a coiled tubing wireline head 604 of the orienter 606. The orienter 606 may include an orientor shaft that provides bi-directional, continuous rotation (reference numeral 608).

The MWD module 130 may include a variety of sensors in block 307, such as, for example, D&I sensors and/or a gamma ray (G/R) sensor, which can be eccentrically mounted and/or shielded and positioned to generate azimuthal measurements and images of the borehole. As illustrated by reference numeral 612 and appreciated by one of ordinary skill in the art, the LWD module 120 may support directional, formation, and evaluation measurements. For example, the LWD module 120 may include resistivity sensors that may be constructed with tilted coils or other non-axisymmetric directional sensors for enabling the generation of azimuthal measurements and images of the borehole.

When the orienter 606 is rotating the CTD BHA 200 in a continuous mode, the data acquired can be used to generate an image covering 360 degrees of the borehole. The sensors may be powered and data transmitted to the surface via the wireless power and data connection 304 through the orienter 606 to the head 604 that connects to the wireline 602 and coiled tubing 204. It should be appreciated that the continuous rotational capability of the CTD BHA 200 may allow drilling a straight trajectory and maintaining precise well placement in the reservoir by rotational images and geo-steering measurements.

FIG. 20 illustrates a more detailed view of the orienter 606 and the wireless power and data connection 304. The orienter 606 may be located above the other BHA components (the LWD module 120, the MWD module 130, and the drilling motor 306). To facilitate communication under various rotational positions and under continuous rotation, the wireless power and data connection 304 is used. The orienter 606 can be used to hold a certain rotational position or toolface in the BHA when changing the well trajectory or continuously rotate the BHA to maintain the well trajectory.

The rotating element of the orienter 606 is connected to the MWD module 130 and passes power and data between the MWD module 130 and the LWD module 120 to the stationary element in the orienter 606, which conducts data and power between the surface and the CTD BHA 200 via the wire-line 602 located in the coiled tubing 204. Power and data may be transmitted between the stationary coil 506 and the rotating coil 504 via tuned-inductive methods as described above in connection with FIGS. 2-14.

The CTD BHA 200 is rotated by an orienter mechanism that includes a wire-line powered motor and gear box 702 mounted in the stationary body of the orienter 606. An output shaft of the gear box may be coupled to an adapter subassembly, which connects to the connection 508. Various system electronics may be mounted in a main body of the orienter 606. The stationary body of the orienter 606 may also include optional auxiliary measurements such as internal and annular pressure measurement elements 704 a and 704 b.

Although only a few embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from this invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims.

In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, sixth paragraph for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. 

What is claimed is:
 1. A method for operating a drilling assembly, the method comprising: providing a first coil within a second coil; coupling the first and second coils with a coupling coefficient, k, wherein, k=M/√{square root over (L₁L₂)}≦0.9, M is a mutual inductance between the first and second coils, L₁ is a first self-inductance of the first coil, and L₂ is a second self-inductance of the second coil; and resonantly tuning the first coil at a first frequency, f₁, with a first capacitance, C₁, and the second coil at a second frequency, f₂, with a second capacitance, C₂, wherein f₁ is approximately equal to f₂, ${f_{1} = {{\frac{1}{2\pi \sqrt{L_{1}C_{1}}}\mspace{14mu} {and}\mspace{14mu} f_{2}} = \frac{1}{2\pi \sqrt{L_{2}C_{2}}}}};$ wherein the first and second coils have a figure of merit, U, wherein U=k√{square root over (Q₁Q₂)}≧3, ${Q_{1} = \frac{2\pi \; f_{1}L_{1}}{R_{1}}},{Q_{2} = \frac{2\pi \; f_{2}L_{2}}{R_{2}}},$ Q₁ and Q₂ comprise respective quality factors associated with the first and second coils, and R₁ and R₂ comprise respective resistances of the first and second coils.
 2. The method of claim 1, wherein the first and second coils comprise cylindrical wire coils.
 3. The method of claim 2, wherein the first coil comprises an inner coil comprising a wire wrapped on a core of material having a relatively high magnetic permeability.
 4. The method of claim 3, wherein the material comprises ferrite.
 5. The method of claim 2, wherein the second coil comprises an outer coil surrounded by a cylinder of material with a relatively high magnetic permeability.
 6. The method of claim 5, wherein the material comprises ferrite.
 7. The method of claim 1, further comprising: approximately matching a source impedance of the first coil, R_(s), with a load impedance of the second coil, R₁, wherein R_(S)≈R₁√{square root over (1+k²Q₁Q₂)}.
 8. The method of claim 1, further comprising: approximately matching a load impedance of the second coil, R₁, with a source impedance of the first coil, R_(s), wherein R_(L)≈R₂√{square root over (1+k²Q₁Q₂)}.
 9. The method of claim 1, wherein the first coil is coupled to a rotor of a positive displacement motor (PDM), and the second coil is coupled to a drill collar of the PDM.
 10. The method of claim 1, further comprising: passing drilling fluid through a passage between the first and second coils.
 11. The method of claim 1, further comprising: transmitting power between the first and second coils.
 12. The method of claim 1, further comprising: transmitting data between the first and second coils.
 13. The method of claim 11, wherein the transmitting data between the first and second coils comprises modulating one of an amplitude, a phase, and a frequency of a current.
 14. A system for transmitting power or data communications in a drill string, the system comprising: a drilling assembly comprising an inner cylindrical coil located inside an outer cylindrical coil, wherein the inner cylindrical coil is adapted to rotate with respect to the outer cylindrical coil, rotate around an axis of the outer cylindrical coil, or move axially with respect to the outer cylindrical coil.
 15. The system of claim 14, wherein power is transmitted between the inner and outer cylindrical coils.
 16. The system of claim 14, wherein data communications are provided between the inner and outer cylindrical coils.
 17. A bottom hole assembly (BHA) for use in a coiled tube drilling system, the BHA comprising: a measuring-while-drilling (MWD) module configured for coupling to coiled tubing; and a wireless power and data connection disposed above a drilling motor for providing power and data connectivity between the MWD module and the drilling motor.
 18. The BHA of claim 17, further comprising: a rotary steerable system (RSS) coupled to the drilling motor for receiving power from and communicating with the MWD module via the wireless power and data connection and the drilling motor.
 19. The BHA of claim 18, further comprising a drill bit assembly coupled to the RSS, and wherein the wireless power and data connection comprises an inductively coupled pair of coils comprising a primary coil and a secondary coil.
 20. The BHA of claim 17, further comprising: an orienter configured for coupling to coiled tubing and receiving a wireline conductor disposed in the coiled tubing; wherein the wireless power and data connection provides power and data connectivity to one or more downhole components of the BHA. 